Stabilization of organic substances



Patented Oct. 11, 1949 STABILIZATION OF ORGANIC SUBSTANCES Roger W. Watson, Chicago, Ill., and Clarence M. Loane, Hammond, Ind., assignors to Standard Oil Company, Chicago, 11]., a corporation of Indiana No Drawing. Application March 28, 1946, Serial No. 657,892

13 Claims.

The present invention relates to the stabilization of organic substances against oxidative deterioration in the presenceof metals which catalyze the oxidation, for example copper, vanadium, chromium and the like. More particularly, the present invention is directed to the stabilization of petroleum products against oxidative deterioration in the presence of copper or compounds thereof and to such stabilized products.

Organic substances such as petroleum products, for example, motor fuels, naphthas, fuel oils, electrical insulating oils, lubricating oils, greases, waxes and asphalts, compounded lubricants, synthetic hydrocarbon oils, vegetable oils, animal oils, marine oils, vegetable juices, textile fibers, antioxidants, rubber and rubber products, soaps, etc. are susceptible to oxidative deterioration which is accelerated by the presence of metals which are oxidation catalysts, for example, copper, vanadium, chromium, etc. or compounds thereof.

An example of such oxidative deterioration is the formation of gum and/or color under storage conditions of certain types of motor fuels, particularly those obtained from cracking processes. In order to inhibit such gum and/or color formation, it has been common practice to add to such fuels various types of antioxidants such as for example, aminophenols, substituted aminophe nols, naphthols, aromatic hydroxy compounds, hardwood tar distillates and other known antioxidants. It has been observed that when motor fuels containing antioxidants are stored in metal containers or come in contact with metal surfaces containing copper or copper alloys, the inhibiting effect of the antioxidant is decreased to the po nt where such fuels form gum in Spite of any antioxidant they may contain. The deterioration of antioxidants is also encountered in fuels which have been subjected to the copper chloride sweetening process.

It is an object of the present invention to provide a method of inhibiting the oxidative deterioration of organic substances in the presence of metals which are oxidation catalysts. Another object of the invention is to provide a class of,

inhibitors which, when added to an organic substance normally susceptible to oxidative deterioration in the presence of metals which are oxidation catalysts, will inhibit or suppress the activity of such metals. Another object of the invention is to provide a, new class of metal deactivators. Another object of the invention is to provide a class of organic compounds, which when added to an organic substance containing an antioxidant, will increase the .efliciency of the antioxidant in the presence of metals of compounds thereof which are oxidation catalysts. Still another object of the present invention is to inhibit the oxidative deterioration of petroleum hydrocarbons containing or in contact with metals or metal compounds which catalyze such oxidative deterioration. Other objects and advantages will be come apparent from the following description thereof.

We have discovered that the oxidative deterioration of organic substances can be effectively inhibited or suppressed by adding to such organic substances an organic dithiooxamide. These organic dithiooxamides have the following general structures:

H H R -I lC-Cl I-R R1-N=C--C=NR| i s St in which R and R. are hydrogen or organic groups such as aliphatic, cyclic aliphatic, aromatic or heterocyclic groups. The substituents R and R may be the same or different groups and may contain substituents such as alkyl, aryl, alkoxy, aryloxy, hydroxy, halogen, nitro, cyano, carboxyl, and amino groups. The organic dithiooxamides employed in the present invention include linear condensation products resulting from the reaction of a dithiooxamide with a polyamino compound containing at least two primary amino nitrogen atoms, for example alkylene polyamines such as ethylene diamine, diethylene triamine, triethylenetetraamine, tetraethylene pentamine, propylene diamine, and other polyamino compounds, for example aminopiperazines, tolylenediamine, diaminobenzene, diaminopyridine, etc. These linear condensation products may be represented by the general formula:

wherein R and R are as above defined, n is at least one, and Z is a residue from a polyamino compound; that is, the residue obtained from a polyamino compound when two primary amino groups are removed.

Many organic substances are inhibited against oxidative deterioration by the addition thereto of small amounts of antioxidants. However, in the presence of certain metals, such as for example copper, vanadium, chromium, iron, cobalt or com pounds thereof, the oxidation inhibiting effect of such antioxidants is materially reduced. The above described class of compounds are particularly effective as metal deactivators in suppressing or inhibiting the deteriorating effect of such metals on antioxidants.

The dithiooxamides are readily prepared by reacting cyanogen with hydrogen sulfide according to the following equations:

The nitrogen substituted derivatives of the dithiooxamide are obtained by heating the dithiooxamide at a temperature of about 200 F. with an amine. This reaction is represented by the following equation:

The linear condensation products above described can be readily prepared by reacting an organic dithiooxamide with a polyamine. This is illustrated by the following equation in which dimethyldithiooxamide is reacted with ethylene diamine:

Condensation compounds formed by the reaction of any of the above compounds with one of the following polyamines:

Ethylene diamine Propylene diamine B,B',B" triaminotriethyl' amine Triethylene tetramine Diethylene triamine Dipropylene triamine Tolylene diamine Tetraethylene pentamine B,B',B" triaminotripropylamine Phenylene diamine While all of the organic dithiooxamides are efiective inhibitors, it is not to be implied that all are equivalent since the specific activity of the various compounds varies to some extent.

The effectiveness of the herein-described compounds as inhibitors against oxidative deterioration, particularly 'in the presence of metal catalysts, is illustrated by the following data obtained by subjecting a motor fuel containing an antioxidant, in the presence of a metal or metal compound, to the A. S. T. M. method for determining the stability of gasoline by accelerated oxidation. This test method havin A. S. T. M. designation D525-42T is fully described on page 965 of the A. S. T. M. Standards of 1942, Part III. In mak- The amount of the inhibitor added to the organic material to be protected against oxidative deterioration will vary with the amount of catalyst present and the activity of such metal. A small amount sufficient to inhibit the oxidative deterioration should be employed, for example from about 0.0001% to about 1%, and preferably from about 0.001% to about 0.1% of the inhibitor based on the organic substance. It is to be understood of course that greater amounts can be employed as'conditions warrant.

Specific examples of organic dithiooxamides which can be employed in accordance with the present invention are:

Dithiooxamide N-methyldithiooxamide N-ethyldithiooxamide N-propyldithiooxamide N-isobutyldithiooxamide N-cyclohexyldithiooxamide N-octyldithiooxamide N-dodecyldithiooxamide N-hydroxyethyldithiooxamide N-aminoethyldithiooxamide N-ortho-hydroxyphenyldithiooxamide N,N' -diisopropyldithioox amide N,N'-di-o-hydroxyphenyldithiooxamide N,N-di(aminoethyl) dithiooxamide N,N'-di(hydroxyethyl) dithiooxamide N,N'-di-o-aminotolyldithiooxamide N-methyl, N'-allyldithiooxamide N-butyl; N-pheny1dithiooxa mide ing this test, the blank was a motor fuel containing about 0.01% butylaminophenol as the The soluble copper employed in the above I test was copper oleate used in a concentration of four milligrams per liter, and the metallic copper was eighteen inches of No. 18 copper wire in each test bomb.

As shown by the above data, the dithiooxamide very effectively maintained the inhibiting effect of the antioxidant in the presence of soluble copper as well as metallic copper. The commercial metal deactivator however was inefiective in the presence of metallic copper.

While we have described our invention in connection with the stabilization of motor fuels, it is not limited thereto but is applicable to the stabilization of organic substances, such as for example those hereinbefore mentioned. When employed in lubricants, such as lubricating oils and greases, turbine oils, insulating oils and the like.

the herein-described metal deactivators can be used in conjunction with antioxidants, anti-rust compounds, pourpoint depressants, detergents, anti-wear agents, anti-foam agents, bearing corrosion inhibitors, etc.

While we have disclosed the preferred embodiments of ourinvention and the preferred modes of carrying out the same in eflect it will be readily apparent to those skilled in the art that many variations and modifications may be made without departing from the spirit of our invention.

We claim:

1. An oleaginous organic material selected from the group consisting of a hydrocarbon oil and a fatty oil, which is normally susceptible to oxidative deterioration in the presence of a metal and compounds thereof which catalyze said oxidative deterioration, containing an organic dithiooxamide in small but sufilcient quantities to suppress the oxidative catalyzing effect of said metal and compounds thereof.

2. A composition as described in claim 1 in which the dithiooxamide is an alkyldithiooxamide.

3. A composition as described in claim 1 in which the dithiooxamide is dimethyldithiooxamide.

4. A composition as described in claim 1 in which the dithiooxamide is an aryldithiooxamide. 5. A composition as described in claim 1 in which the dithiooxamide is di(o-amino-phenyl) dithiooxamide.

' 6. An oleaginous organic material selected from the group consisting of a hydrocarbon oil and a which the organic dithiooxamide is a dialkyldithiooxamide.

8. A normally liquid petroleum hydrocarbon,

normally susceptible to oxidative deterioration in the presence of a metal and compounds thereof which normally catalyze said oxidation, containing an organic dithiooxamide in small but sufiicient quantities to suppress the catalyzing efiect'of said oxidationcatalyst.

9. A composition as described in claim 8 in which the organic dithiooxamide is a dicycloalkyldithiooxamide.

10. A composition as described in claim 8 in which the organic dithiooxamide is a dialkyldithiooxamide.

11. 'A composition as described in claim 8 in which the organic dithiooxamide is dimethyldithiooxamide.

12. A composition asdescribed in claim 8 in which the petroleum hydrocarbon contains in addition to said organic dithiooxamide a small but sufiicient amount of an antioxidant normally effective to inhibit the oxidative deterioration of said petroleum hydrocarbon in the absence of the oxidation catalyst but normally ineffective to inhibit said deterioration in the presence of said oxidation catalyst.

13. A composition as described in claim 9 in which the petroleum hydrocarbon contains from about 0.0001% to about 1% of said organic dithiooxamide.

ROGER W. WATSON. CLARENCE M. LOANE.

UNI'IIEHD STATES PATEN'IS Number Name Date 2,352,164 Burnham June 27, 1944 2,396,156 Clarkson Mar. 5, 1946 OTHER REFERENCES Voznesenskiiet al., Chemical Abstracts, vol. 34, page 4057, (1940).

Certificate of Correction Patent No. 2,484,257 October 11, 1949 ROGER W. WATSON ET AL.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows:

Column 6, line 28, for the claim reference numeral 9 read 8;

and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Office. Signed and sealed this 14th day of February, A. D. 1950.

THOMAS F. MURPHY, 1 Assistant Gommz'ssioner of Patents. l

Certificate of Correction October 11, 1949 Patent No. 2,484,257

ROGER W. WATSON ET A certified that error appears in the printed specification oi the above quiring correction as follows:

for the claim reference numeral should be read with this correc of the case in the Yatent Ofl'lce.

It is hereby numbered patent re Column 6, line 28, and that the said Letters Patent same may conform to the record Signed and sealed this 14th day of February, A.

9 read 8;

tion therein that the THOMAS F. MURPHY,

Assistant Commissioner of Patents. 

